81900131 has 2 divisors, whose sum is σ = 81900132. Its totient is φ = 81900130.

The previous prime is 81900121. The next prime is 81900139. The reversal of 81900131 is 13100918.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81900131 - 2¹⁰ = 81899107 is a prime.

It is a super-2 number, since 2×81900131² = 13415262915634322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81900097 and 81900106.

It is not a weakly prime, because it can be changed into another prime (81900139) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40950065 + 40950066.

It is an arithmetic number, because the mean of its divisors is an integer number (40950066).

Almost surely, 2^81900131 is an apocalyptic number.

81900131 is a deficient number, since it is larger than the sum of its proper divisors (1).

81900131 is an equidigital number, since it uses as much as digits as its factorization.

81900131 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 216, while the sum is 23.

The square root of 81900131 is about 9049.8691150756. The cubic root of 81900131 is about 434.2717033397.

The spelling of 81900131 in words is "eighty-one million, nine hundred thousand, one hundred thirty-one".